Most modern communication devices, especially portable communications devices such mobile or cellular telephones, comprise at least two speakers. Typically for instance there may be a first loudspeaker located on the device, e.g. for audio media playback. This first loudspeaker may for example be located towards the bottom of the device. In addition there is typically also an earpiece receiver loudspeaker (i.e. a second speaker) at a different location on the device, typically towards the top of the device or otherwise at a location near where a user's ear may be expected to be in use (if not using an accessory such as a headset or using the device in a speakerphone type mode).
FIG. 1 for example illustrates a device 100, which in this example may be a mobile telephone, having a side ported first loudspeaker 102 at a first location on the device and also having an earpiece receiver speaker 104 at a different location.
In most common configurations the earpiece speaker and first loudspeaker are used for different functions and typically the first loudspeaker can generate a much greater sound pressure level (SPL) than the earpiece. The earpiece receiver speaker (which will be referred to herein simply as an earpiece or earpiece speaker) is typically used as the output device during handset calls (without an attached peripheral device such as a headset), when it is expected that the device is held next to the user's ear. The first loudspeaker may be used as the the output device during music playback and speaker phone mode calls.
The first loudspeaker may therefore typically be of the order of 8 Ohm, and may be driven for example by a 5V-10V boosted D or G class amp which is capable of driving around 4 W in to the speaker. The earpiece may typically be of the order of 32 Ohm, and may for example be driven by a 2.5V A/B class amp which is capable of driving around 100 mW in to the earpiece speaker.